The invention relates to a fluid driven differential. More particularly, the invention relates to a differential that employs fluid to transfer rotary motion from a drive shaft to the wheels in an automobile drive train.
Conventional automobiles employ a differential to distribute power from a drive shaft-which often extends longitudinally in an automobile, to the wheels, each of which typically have an axis that is transverse to the drive shaft. The differential often is used to control the distribution of power to the wheels, whereby under certain conditions, one wheel will get more power than the other wheel.
The drive ratio of a standard differential is generally fixed. Accordingly, other than controlling slippage in low traction situations, the final drive ratio cannot be varied.
U.S. Pat. No. 3,627,072 to Smirl discloses a hydraulic clutch for four wheel drive vehicles, whereby a fluid pressure source is used to urge the clutch into a fully engaged condition only when the transmission is in a forward mode of operation.
U.S. Pat. No. 3,730,315 to Annis et al. discloses a hydrodynamic device with a slipping mechanical clutch. U.S. Pat. No. 3,744,348 to Lemon discloses a planetary transmission mechanism that includes a hydraulic control mechanism that is adapted to control engagement of friction engaging devices for establishing various drive rations thought the gear train. U.S. Pat. No. 4,181,203 to Malloy discloses a positive displacement hydraulic mechanism for controlling the engagement of a slipping clutch in parallel drive relationship with a torque converter. U.S. Pat. No. 4,673,055 to Yamaoka et al. discloses a transmission for self-propelled vehicles that employs a fluid-actuated clutch for interrupting input of power to the speed change mechanism before shifting operations.
While these units may be suitable for the particular purpose employed, or for general use, they would not be as suitable for the purposes of the present invention as disclosed hereafter.